These include memory formation, feelings, and behaviours relevant for neurological and psychiatric disorders, as well as processes involved in infectious disease.
The 2026 Nobel Prize in Physiology or Medicine , awarded to Karl Deisseroth, Peter Hegemann, and Georg Nagel “for their discoveries concerning light-gated ion channels and optogenetics ”, has brought renewed attention to using light to investigate fundamental biological processes.
For Nishith Gupta, professor of Biological Sciences at BITS Pilani, Hyderabad, and founder of the Intracellular Parasite Education and Research Labs (iPEARL), the recognition has a personal significance in his own scientific journey. Mr. Gupta’s decades-long collaboration with Hegemann at Humboldt University of Berlin, where Hegemanna is Hertie Senior Professor of Neuroscience, helped extend optogenetic approaches beyond neuroscience into his study of Toxoplasma gondii, an intracellular parasite that infects humans, mammals, and birds. Optogenetics enables scientists to control selected cells or biological processes using light-sensitive proteins. The Nobel Committee for Physiology or Medicine stated: “It all began with Peter Hegemann’s curiosity. He wondered how Chlamydomonas, a single-celled alga, is able to swim towards a light source. In the early 2000s, he and Georg Nagel discovered channelrhodopsin, an algal protein with unique properties, found on the surface of the cell. When it is illuminated by blue light, a channel opens through the protein. Charged ions then flow into the cell, creating an electrical impulse. They found that regardless of which cell they put the protein in, those cells became light sensitive. Put simply, the researchers showed that light controls the enzyme, the enzyme produces cAMP, and cAMP helps regulate what happens inside the parasite (Toxoplasma gondii): how it enters cells, moves, and exits cells. Mr. Joint funding from the German Research Foundation (DFG) supported their collaboration. After Mr. Gupta relocated to India, Mr. Hegemann continued to support his research through Mr. Gupta’s Wellcome Trust–DBT Senior Fellowship project at BITS Pilani. Researchers from his team continued to visit Hegemann’s group in Berlin.
In 2005, Deisseroth showed that introducing channelrhodopsin into rat neurons allowed blue light to trigger nerve signals. In 2007, he showed light-based control in mice. This landmark study was published in the Journal of Biological Chemistry in 2013.
Gupta says that working alongside Hegemann in Berlin, with their laboratories in neighbouring departments, was an important part of this scientific journey.
